Microfacies analysis and depositional environment of Gadvan and Dariyan formations in Lar anticline in North of Gachsaran
Microfacies and depositional environment of Gadvan and Dariyan Fms. In Lar anticline section in North of Gachsaran (South Dezful Embayment) are investigated in this study. The Gadvan Fm. (Barremian ? Aptian) with khalij mbr. Have 77.8 meters thickness and consist of grag shales and fossiloferous thin bedded limestones. The Lower contact of this Fm. With Fahliyan Fm. Are tranliyan Fm. And the upper contact with Dariyan Fm. Are transitional. Dariyan Fm. (Aptian) has 37 meters thickness and contains thin to medium bedded nodular ,rubly and argilacious limestones with interlayers of cherts. The upper contact of this Fm. With kazhdumi shales is transitional. Field and microscopic studies in this section have lead to recognize two microfacies groups which related to open marine (A) and lagoonal (B) sub ? environments that had been deposited in a homoclinal carbonate ramp. Vertical facies changes in these Fms. Show two 3rd ? order depositional sequences.